Functional treatment of unilateral posterior crossbite improves condylar asymmetry in mixed dentition patients.

Abstract

Background/objectives: This study's aim was to evaluate the effects of unilateral posterior crossbite (UPXB) treatment with the appliance Function Generating Bite (FGB) on the asymmetry of mandibular condyles and rami.

Materials/methods: This retrospective study included 156 patients: 52 with UPXB (F = 30, M = 22, mean age ± SD = 7.9 ± 1.5 [yr.mo]) treated with FGB, 104 age and gender-matched control subjects without the malocclusion (control-T0: N = 52, F = 30, M = 22, mean age ± SD = 8.2 ± 1.3; control-T1, n = 52, F = 30, M = 22, mean age ± SD 9.7 ± 1.2). Pre- (T0) and post-treatment (T1) orthopantomographies were analyzed by finding the intersection between a line tangent to the lateral profile of the condyle and ramus and a perpendicular line tangent to the condylar head; the intersection and tangent points were used to measure condylar and ramal heights and to calculate the percentage difference between the sides (asymmetry index). Cephalometric analysis was performed on lateral skull X-rays taken at T0 and T1.

Results: Condylar asymmetry was significantly increased in UPXB at T0 (P < 0.00001) but not at T1. Between T0/T1 the asymmetry was significantly reduced (P < 0.01). Cephalometric analysis showed that mandibular clockwise rotation was significantly increased in UPXB at T0 (P < 0,01) but not at T1, when the clockwise rotation was significantly reduced (P < 0.05).

Limitations: This study did not include an untreated UPXB group and did not evaluate condylar morphology, Conclusions/implications: Functional treatment of UPXB with FGB was associated with a significant reduction in condylar asymmetry and significant mandibular repositioning, highlighting that FGB could rebalance condylar growth in developing patients.